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1.
Michiel Janssen Prof. Dirk E. De Vos 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(45):10724-10734
The practical application of Shilov-type Pt catalysis to the selective hydroxylation of terminal aliphatic C−H bonds remains a formidable challenge, due to difficulties in replacing PtIV with a more economically viable oxidant, particularly O2. We report the potential of employing FeCl2 as a suitable redox mediator to overcome the kinetic hurdles related to the direct use of O2 in the Pt reoxidation. For the selective conversion of butyric acid to γ-hydroxybutyric acid (GHB), a significantly enhanced catalyst activity and stability (turnover numbers (TON)>30) were achieved under 20 bar O2 in comparison to current state-of-the-art systems (TON<10). In this regard, essential reaction parameters affecting the overall activity were identified, along with specific additives to attain catalyst stability at longer reaction times. Notably, deactivation by reduction to Pt0 was prevented by the addition of monodentate pyridine derivatives, such as 2-fluoropyridine, but also by introducing varying partial pressures of N2 in the gaseous atmosphere. Finally, stability tests revealed the involvement of PtII and FeCl2 in catalyzing the non-selective overoxidation of GHB. Accordingly, in situ esterification with boric acid proved to be a suitable strategy to maintain enhanced selectivities at much higher conversions (TON>60). Altogether, a useful catalytic system for the selective hydroxylation of primary aliphatic C−H bonds with O2 is presented. 相似文献
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Vsevolod Khikhlovskyi Albert J. J. M. van Breemen Jasper J. Michels René A. J. Janssen Gerwin H. Gelinck Martijn Kemerink 《Journal of Polymer Science.Polymer Physics》2015,53(17):1231-1237
In many organic electronic devices functionality is achieved by blending two or more materials, typically polymers or molecules, with distinctly different optical or electrical properties in a single film. The local scale morphology of such blends is vital for the device performance. Here, a simple approach to study the full 3D morphology of phase‐separated blends, taking advantage of the possibility to selectively dissolve the different components is introduced. This method is applied in combination with AFM to investigate a blend of a semiconducting and ferroelectric polymer typically used as active layer in organic ferroelectric resistive switches. It is found that the blend consists of a ferroelectric matrix with three types of embedded semiconductor domains and a thin wetting layer at the bottom electrode. Statistical analysis of the obtained images excludes the presence of a fourth type of domains. The criteria for the applicability of the presented technique are discussed. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1231–1237 相似文献
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H. C. J. Hoefsloot H. W. Hoogstraten L. P. B. M. Janssen 《Applied Scientific Research》1990,47(4):357-377
A liquid layer containing a single solute is bounded on the outside by a rigid spherical surface and on the inside by a concentric gas/liquid interface. The solute evaporates from the liquid to the gas phase and, if the surface tension depends on the solute concentration, surface-tension driven convective flows may arise (Marangoni instability). Assuming zero-gravity conditions and using a normal-mode approach, we study the linear stability of the time-dependent, spherically-symmetric concentration profiles in a motionless liquid. Numerical results are presented for Marangoni numbers and perturbation wave numbers in the case of neutral stability. It turns out that the system's stability properties are strongly dependent on the curvature of the interface and on the mass-transfer Biot number. 相似文献
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Mathematical deconvolution methods can separate co-eluting peaks in samples for which (chromatographic) separation fail. However, these methods often heavily rely on manual user-input and interpretation. This is not only time-consuming but also error-prone and automation is needed if such methods are to be applied in a routine manner. 相似文献
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During electron spin resonance studies of radical-anions1 of the thiophene analogues of fluorenone (cyclopentadithiophenones, IA-VIA) and dibenzothiophene-dioxide (dithienothiophene-dioxides, IB-VIB) deuteriumhydrogen exchange phenomena were observed. 相似文献
9.
R. A. J. Janssen D. Moses N. S. Sariciftci A. J. Heeger 《Molecular Crystals and Liquid Crystals》2013,570(1):921-926
Abstract Photoexcitation of a nonathiophene in film or solution across the π-π* energy gap produces a metastable triplet state. In the presence of C60, on the other hand, an ultra fast electron transfer from the photoexcited nonathiophene onto C60 is observed in films, whereas in solution C60 is involved in an efficient energy transfer reaction with the triplet-state nonathiophene. 相似文献
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